Discriminating acoustic signal detector



` *"Tlns invention relatee to `detectors foraconstic ing surroundings and itlias for its main object tov L providemeansor producing a local readily dis tnguisiialqle unmistakable signal Whenever o."

V` sound. ,produc 'ig surroundings might remain ori--` noticed oijmiglit escape attention.

decine surroundings signals can'onljy engage atcial discriminating character distinguishing them l fclearlv from other sounds, usually termed I'irioisef their intensity i5 lliglrcafbove the noise produced. "As nature and intensity'o signa-ls are repeatedly `haveto h'eused tomakesiicli signals audible so {"vert them into audible or visible signa-ls, merely f "released when signals are delivered, but not pro-s ronndings.'

`It isithereioi'e.- a yprimary object to provide signal, which are adapted to ce relayed or to be Ving. them but which are not operated by the surrounding'noise itseii. t is furthe?` objectof the inventionto provide means which are lcapable of distinguisliine signals, for iiclstence signals given on a road by the users ory the road, from surrounding noise,v for instance i rounding noise to such an extent as v.torna ticallv attention. 2 Y v it is a girilier object of the invention to provide are separate from and not influence j v .sounds or noises atthe place where the ,s .11s are to ce delivered, for instance, by those nois s which arefendiblewithin the cabin oa truck. I 'It is a further object of the inv entier'. to provid [eiectronicmeans capable of distinguishing ``ceacousticv signals rising above thez:x,'ever 1`to a slight degree and to operate local signals merely` "s 'vlsnchane-coustic signal has been received.' v`

sound signa-l is received which on account of the *g It is a vvelll known facttllat Within sound pro-y l l tention automatically if they are eitherof a spef aetors'which cannot be controlled speoialmeans fasteenffageattention' automatically, or toconmeans; adapted .to neoperated by a given type oil aceusticsignai and notreqniring a lspecial type of Y 1 released by the inci'lming signals only es soon as, they are-distinguen able from the noise surround the noise made by a moving truck, even if' their` v intensity dees notv rise above that of the sur- `to engage au i f vtween nadie-found noises whatever tleiz' level andl when It is a'furtlier object of the invention to. provide electronic' means consisting ci d ijectier for Asigi.

eczeem. fcc-i. live524 ose DXSCRIRHNATENG ACGUSEEC SIGNAL- Y nernofro t t einem; Hastings, New., ne Marne l f Carmody, Parksten, VS. Delig;

' nal currents and of an eiectroniccurrntcarying" signals which are received wtliin'sound produ' f tube, connected with the same, which control a y permanently energized circuit, cle-energized oy the action of the increasing volte-ge of the recti.

ed signal current in the electronic-tube, a iocal i zation. .v l

duced bythencise orscundsgenerated in thesur invention.

Further and more specic objects will be appar? Y ent from the following detailed specicetion-` The invention is illustrated in the accompanieingdreivng showing one embodiment of ine-inv venticn and 'a modification thereof. It is howf ever to be .lnderstood that il arengements shown and described are examples selected in- 'e 'i isan elevational sidevievv of e truck equipped with the device embodying the .invention and showing onernode o application of the Figure 2 is a diagram of comiections.` n Fi stage -V -As ein-ive explained the purpose of the yin'vention Y tlfe production of a distinctive signal reproducing: Snc-.1

aing signalvflien thelatter isreceived Y ork diflicolt in the oase of an acoustic' signal re- Viecepion means for the signalfsounds coming from'theoutside, such for instance', as the signals `:given oy users of a road to other,vehiclegwhicz l by the.

Vceived in surroundings in which sounds usualljyyl termed noise" are continuously producedrom 'sources einer then ythe source of signa-ls;y At a certain intensity `level of toe local sounds produced an incorfing acoustic signal, even of greater in# .an said sounds, is no longer ele'erif.1 dished;

` a specieily selected signal. or an'optical signal merely the 'problem (1f-distinguishing an other-'- wis-3, eleari.7 defined and `clearly received incertiV l fing signal from other sounds which aire locally' produced` Tneproblem is more diiicultivhenl reception of van acoustic signal has to vtalxelplacej.` i under conditions Ainlwhich the signal isfreceivecl'` l NoV essence of.

ore 3 is a modification ci this diagram, sininv` ing tee oi a single' combined tube inv t'nelast f n it therefore necessary to provideV Acial arrangement n'order to produce a disand lisof an in` Q tensity'only moderately above' tbat'o tliesur--` ffm example orcases 'of this type is the reccp i tion offan acoustic signal on a moving truck. The i `v 'driver of the truck should be able to hear those l of vthe road. In actual practice hais prevented frcrnlliearing such signalsby the noise in the f reception of the'signal `ata point outside the )be meentedine ',evei'oi the noise sounds produced by the truc-kat this pcintis very high. -T

the driversfcabin are added.

gage attention;

` The object ofthe invention is therefore to proy f `vide auYarrangernern;` which discriminates suiv v l Yicently between the noise produced permanent-` Y acoustic signals which are given `by other users'` l fascisme f' l `themes 2|. The piace zi aftasten@ 2l is erinectecl with the B battery as usual; the cathode'V circuit 2&,Yincluding the cat-hotles 25 of the tube crates drvers cabin vdue .to the engine, the gearing, the j chainV transmission and the'movements, and vi`v brat-ions of tie'parts of` the moving vehicle. The j c Y .l5` orivers cabin and the reproduction of the signal `in tbecabinljwll in itself not provide a remedy f 'because atany point atm-lien the pick upinay;

duction of the noise, sounds to which the noises Ain ly inthe surroundingsyof the piek Vup andthe i' acoustic signals received from other sources, suoli as` for iii-stance from "operate specially generated signals in the drivers ythe rear `ol the trucker at some other point as possible on'anevenfevel duringV operation. This microphone is connected with an amplifier,

Y which is of the conventional 'type and is shown as aresistancev coupled two stage triocle amplifiezy Ythe triodes beingl indicated at. 8 and S, the cou- L cling condensers at IG, iLthe resistances in the `that other tubes or other couplings between the drawing is not of special significance. The microrst amplifier tube' by means of condenser. it I and,resistance FT. A source for plate voltage is at E and a source of current supply for Y n heating the ilaments at A. These sources of ourl. rent 'may be special batteries or generators or they may derive their power irom'tne sources' of. cwer of the car byany` one vfor. this purpose. f

Y' sists of a combination of tubes or of a combined tube. one-of them being a rectier 25, the other "i9, connected with `the output circuit ofthe piiier by means ofcondenser H. The c o'miec-- eient intensity and of `such a/character as to be` wherethe noise produced in its vicinity 'is as for plate circuit t2, i2 and the resistentes in the gridcircuits-at iii, i5; Itmay be emphasized pbcne 5 may-be connected with the grid i2 of the amplifier. These tubes are jointed by a detector" circuit coupled 'to-:the output circuit ofthe am' other users of the marito l.

cabin, exclusively produced `by the incomingl These special signals need not neces- 20 and 26,01 tube 2i, contains a relay Sil herringv yan annature 2S with relaycontacts 31,.` 32 which areV part-of asgnal circuit `33. The latter op:- l

a signal vformeel either bya lamp '34 or by a horn 35. y Y

i If a hornf is'lused it `arranged close. to the drivers ear and produces a special, easily detect-V Y able signal.

` The annaturet is nely adjustableby :ne-ns v@repriseser. f y "I It benotedthat the elay the example@V shown closes thecircuit 33 whence-energized; Instead of two tubes'a single tube itl of the y #combined type may be used intheterminal stage. j J. as indicated in Figure 3'. `This tube includes two- `diodes 4l ,and a triade irlf'with e. control grid Q3. 2G `reproduetion, ofthe signalwincludes the repio- The .connectiens areessentiallythose above de- Ti'ieresult `is a d signal wl'gich is notsuiiciently distinctive to' enf'v triode and with the 'coupling condenserL El.

. A condenser Se may be connectedacross tha` `diodes and between the `grid andr cathode of the l trioile as'shown in Figures 2 and 3.

l Th'e'cperation Will'be elearfronithe above de` scription. When the micrcmlione and the a..

' plierare switched n, the microphone currents I and 2i., Themicroplione currents are rectified in the diode and a certainl negativel voltage is produced across the diode which will also neim- .pressed on grid IS; but aslong as it does not ex-` ceeda certain .limit does not affect the operation of` thev tube.` Current therefore flows through' i 1 tube 2i 'and energzes relayl. vThe :noise profV 1 rises above the noise level the negative voltage `are afrnpliedl and are delivered over condenser ii to the terminal stage consisting of tubes 2B duced and evenampiified however does not infiuence the "relay, If a Asignal comes in which across the diode increases and therefore the negative voltage of grid i9 reaches the point in j .i

` `which fthe `current through relay Bil is'rut'off.'

Thereby-relay 3571's deeenergiaed` audits armature y snaps *sack and closestlie signal circuit '33 the Y ,lamp lights up or thehorn (f1.5 sounds.

of the means known v Y. a tube 2i providedvwth at least one control grid f When tnesgnal again disappears the relay `is again energized and cuts out the signal ciryeuitSS.. v l v vit will thus be clear that the combination of a.

signal`cu1'rent rectifier with a triode operating ytubesin'ay be used, las the ampiiersoown in ther near the cut oil Voltage with currents` produced 1 at the noise level by amplification o1", the sounds L to noise= and the further combination with j a permane itlyenergized relay, associated with said trocleV andoperating signalcircuit upon the L cutting out oi current through the diode permits to detect sounds which rise above tllenose level According to the invention the last stage con-" j 'by means of springs 31 is shoivnxwhich serves j i. to adjust ythe limits and permits to adjust the.V i amount of current which may still owV through tionA betweenthe tubes 2i! and'Zl is made such i, ,j a way that tbefsignal Voltage is rectified, andr f that the yrf'sctied voltage is applied to the `grid .z

3 and controls the passage .ofV currentthrough and to usethem for signal operation, that j g vspecial signalgin the drivers cabin'may* be operatel cy there which will Anot failfto attractV i attentionautomatically.` .y

The aici-*answeringntl maybe'provided with vari-,v

.ous adjustments for the sound level which has to remain undetected. These' adjustments-v are provided in firstY line by'.v the'suitable [selection` ,and adjustment of the electrical values in the'` diccle-triode -circuit i In addition" only, a fine the trioejbut 'which will. nevertheless cause a ,failing backc the vrelay; Themechanicalad-mv V justmennis vtineforle for effecting a reeacljustinent.

v iiications of the circuit arrangement without `scribed operation. 1

claimed as nervi f criininating betiveenacoustic signals received in 7'" *the veliiclefcoznprisng a detector circuit, in-

It will vlie clear to the expert that the arrange# ment shownmay undergo certain obvious modany departure romfthe intenden and above del; A warninggsignal detector lfor vehicles.` :iis-v the vehicle with` the momentary peak. `values of the sound. of external origin exceeding tennoorar` ily the sound level due Vto sounds `produced on l which may lie made ac- CeSSbB Vto the non-expert in electrical circuits.y

u j a niicrophonicdevice on the vehicle and transf formed into oscillatory currents havinglan externai source of origin and rising 'to momentary peaky valuesandbetween sounds produced on Asound of external origin exceeding temporarily vthe sound level due toY sounds produced on the vehicle, .comprising means for. amplifying the electric oscillations produced andan output cr- `*cuit for the' amplifying means, adetector cirenit joined to said outpntcircuit, saidrdetector f n c v l circuit including a branch with a resistance and Baving described the invention, what 'gisV a parallel branch, the `latter including a Ygricl controlled electronic tube and an electronic rec-` -tiien `the cathodes ol the electronic tube and of the electronic rectifier being connecten,` anf energizing circuit for the saiii' gricl controlled electronic tube and rectier, including the `said cathodes, a signal controlrelay in' saio` energizi.

` ing circuit, a signal circuit controlled by saidj cloning an electronic grid controlled tube with at least one lcontrol grigi adapt-edito cut off the l current flow I through the tubewhen biaseci by 4 an excessive negative voltage, but normally bi' i ased for producing current flow through thetube, l a grounded branch circuit including a resistance parallel to the electronic grid controlled tube,

a Signal controlling vrelay in said energizing cirthrough the tube, signal circuit containing a relay and meansor cutting oi the'current through, the electronic relay and for operating connected with the energizing circuit of the electronic tub-e and 'with the control grid respectively, said rectiiier upon receiptgof a .sienelo'f ina microphonic device on the vcliicle'and trans an energizing circuit for the seid electronic tube.

cuit; normally energized by the cin-rent flow" signal device'close upon cie-energizationof the the `signal ldevicejin the signal circuit 'upon re-V ceipt of a peakv signal rising above the' sound` levelproduced on' the vehiclesaid means inl l cludingan electronic rectier with electrodes,

cutting ofi `the current: new v m VThe following references are of record in the" 1g file otnispatent: i f peak value rectied in the' rectifier producing a v 2. .fr Warning signal detector for vehicles. disy eliminating between acoustic signals receivedv '5o formed into oscillatory currents having an effoternaiscurce of origin and rising to izooinentargg."v peels velues .and between' sounds produced on {rela-y,` closed upon de-energizaltion ofi thefrelay.' a control. grid for said electronic tube joined to the catnoe circuit and connected.` with` the `ln'anoli arranged in parallel to `the resistance "containing branch .and further connected with the plates of the electronic rectier, saisi` griii` current 'passage being l normallyi `biased for through the tube, but being adapted to `cutoff the current interruption through said electrorn'cY tube producing the operation of the signal control relay and thereby operating the local Warm ing signal upon occurrence of a signal of peak vaine surmounting the sound level of the sound i producedv on the vehicle. .l l i FRANK PQ NEE-ER.

nominations errno cierren sTATnsr'A'rnN'rs Eliminer Nainef Datel Y 1,368,736 Vlavigne Feb.` l5, .3321 1 nonnina" PATENTS `Number Country Date 430,459 Great Britain June 19, 11335 432,865 Great Britain i----g Sept. 5, i935 f 458,786 Great Britain Dec. 28,. 19.35,

leonie -Meafrrn .L cannoni. 'if'.

Great Britain Mai'. 30, 1937 I 

